![[Case Western Reserve University -- Toolbar]](/pix/lowpro.gif)
Posted 12-20-99
The universe is like a giant pinball game. In galactic evolution, thousands of galaxies collide, merge, and careen around the night sky. Larger galaxy clusters eat up smaller groups, or two clusters of nearly equal strength -- pulled by their gravitational forces -- might erupt in a fiery battle of tug of war.
This action takes place over millions of years, and nightly observations will note little change. To understand just how volatile the universe is, Christopher Mihos from Case Western Reserve University's Department of Astronomy and his students from his Astronomy 221 and 222 classes employ fast-action computer generated models of galactic collision to study their evolution.
The assistant professor received support from a five-year, $470,000 National Science Foundation Early Career Development Award for his research and teaching project, "The Evolution of Galaxies and Galaxies Clusters." He is taking a two-pronged approach to studying galactic evolution by using computer models and actual observations.
Sean Maxwell, an undergraduate astronomy major interested in computer models, assisted Mihos last summer in designing these computer visualizations.
The astronomer posts his lectures and movie clips on the Web at http://burro.astr.cwru.edu/ for academic and public viewing. His site receives more than 1,000 hits a day. "This is the ability to teach not only your students, but the world," says Mihos.
Students can look at the overall picture of the starry fireworks, or hop on a virtual spacecraft and rocket into the center of the eruption for a front-row seat on galactic changes. The brightly colored models of yellow and blue help students separate stars from interstellar gas.
"These models gives students a three-dimensional feel for what happens in these galactic collisions," explains Mihos.
Another benefit of these movie views is that actual time of these collisions is between 500 million and a billion years, but the computer displays the visualizations in minutes. Another advantage of the computer models is their continuous access, Mihos notes, while telescope observations can take place only on clear nights.
"Instead of sitting back and taking on a passive mode, they now take an active part," Mihos says. "This makes it more of an experimental science."
A decade ago, these astronomical models were available only to researchers, who worked on fast computers with large memories, says Mihos. CWRU's system enables University students to have this tool for classroom instruction.
While students are looking for answers in their classes, Mihos will unravel the evolution of galaxies through his research.
The universe is filled with thousands of galaxy clusters, which range from smaller clusters of 10 to 20 galaxies, to larger clusters with hundreds or thousands of galaxies which started clumping together after the Big Bang at the start of the universe. Very few galaxies remain isolated in the universe, according to Mihos, who also plans to study the reason behind this phenomenon.
This new research advances beyond his ongoing interest in what happens when two galaxies collide.
His starting point is the Local Group, our home galaxy cluster. He is interested in how the Milky Way will react when the giant of our cluster, the Andromeda Galaxy, uses its gravitational might to absorb the Milky Way and many of the smaller galaxies in the group. He eventually plans to search more than 50 million light years away to study the Virgo Cluster, which is home to hundreds of galaxies.
He asks the question, "Does a big, rich, gravitationally bound galaxy cluster evolve differently from a few galaxies off by themselves?"
Other parts of the study will search for tidal debris -- the streamers of stripped stars trailing galaxies as they move through clusters. These tails form when the collision is so violent that some of the galactic matter is flung from the galaxy in the form of stars and gas. The amount of tidal debris offers clues about the violence of the collision, and the presence of dark matter in galaxy clusters.
He will use CWRU's Burrell-Schmidt telescope at the Kitt Peak Station in Arizona for his observations. The telescope with its wide-field camera is undergoing upgrades during this academic year to help detect faint light from stripped stars in galaxy clusters, and infer the presence of dark matter in these clusters.
Details on the Burrell-Schmidt telescope also are available online, at http://burro.cwru.edu/dept/Burrell/burrell.html.
According to Mihos, the trickiest part of taking these picture is the way light bounces off the mirrors and through filters. Each bounce scatters light, which presents a problem for the astronomers, because the scattered light looks like the faint starlight being studied.
The Department of Astronomy is searching for a new technician to design these sensitive changes to the telescope. Paul Harding, a visiting research associate from the University of Arizona, has assisted in making preliminary modifications to the telescope. The new technician will design a new filter to eliminate some of the mirrors and capture the faint starlight in the form of digital images.
"This is a technological challenge to reduce all the areas off which light bounces," says Mihos.
Until the upgrades are completed, Mihos will use the computer models and national telescope facilities for his research.
![[Toolbar]](/pix/ribbon.gif){kind=small}